/**
* Gets a stream to write data to a block. The stream can only be backed by Alluxio storage.
*
* @param blockId the block to write
* @param blockSize the standard block size to write, or -1 if the block already exists (and this
* stream is just storing the block in Alluxio again)
* @param address the address of the worker to write the block to, fails if the worker cannot
* serve the request
* @return a {@link BufferedBlockOutStream} which can be used to write data to the block in a
* streaming fashion
* @throws IOException if the block cannot be written
*/
public BufferedBlockOutStream getOutStream(long blockId, long blockSize, WorkerNetAddress address)
throws IOException {
if (blockSize == -1) {
try (CloseableResource<BlockMasterClient> blockMasterClientResource =
mContext.acquireMasterClientResource()) {
blockSize = blockMasterClientResource.get().getBlockInfo(blockId).getLength();
} catch (AlluxioException e) {
throw new IOException(e);
}
}
// No specified location to write to.
if (address == null) {
throw new RuntimeException(ExceptionMessage.NO_WORKER_AVAILABLE.getMessage());
}
// Location is local.
if (NetworkAddressUtils.getLocalHostName(ClientContext.getConf()).equals(address.getHost())) {
if (mContext.hasLocalWorker()) {
return new LocalBlockOutStream(blockId, blockSize);
} else {
throw new IOException(ExceptionMessage.NO_LOCAL_WORKER.getMessage("write"));
}
}
// Location is specified and it is remote.
return new RemoteBlockOutStream(blockId, blockSize, address);
}
/**
* Obtains a client for a remote based on the given network address. Illegal argument exception is
* thrown if the hostname is the local hostname. Runtime exception is thrown if the client cannot
* be created with a connection to the hostname.
*
* @param address the address of the worker
* @return a worker client with a connection to the specified hostname
*/
private BlockWorkerClient acquireRemoteWorkerClient(WorkerNetAddress address) {
// If we couldn't find a worker, crash.
if (address == null) {
// TODO(calvin): Better exception usage.
throw new RuntimeException(ExceptionMessage.NO_WORKER_AVAILABLE.getMessage());
}
Preconditions.checkArgument(
!address.getHost().equals(NetworkAddressUtils.getLocalHostName()),
PreconditionMessage.REMOTE_CLIENT_BUT_LOCAL_HOSTNAME);
long clientId = IdUtils.getRandomNonNegativeLong();
return new RetryHandlingBlockWorkerClient(
address, ClientContext.getBlockClientExecutorService(), clientId, false);
}
/**
* Obtains a client for a worker with the given address.
*
* @param address the address of the worker to get a client to
* @return a {@link BlockWorkerClient} connected to the worker with the given hostname
* @throws IOException if no Alluxio worker is available for the given hostname
*/
public BlockWorkerClient acquireWorkerClient(WorkerNetAddress address) throws IOException {
BlockWorkerClient client;
if (address == null) {
throw new RuntimeException(ExceptionMessage.NO_WORKER_AVAILABLE.getMessage());
}
if (address.getHost().equals(NetworkAddressUtils.getLocalHostName())) {
client = acquireLocalWorkerClient(address);
if (client == null) {
throw new IOException(ExceptionMessage.NO_WORKER_AVAILABLE_ON_ADDRESS.getMessage(address));
}
} else {
client = acquireRemoteWorkerClient(address);
}
return client;
}